Category: Roof Considerations

RoofPoint is a sustainability guideline developed exclusively for roofing systems. It is similar to other familiar building rating systems such as the U.S. Green Build Council’s Leadership in Energy and Environmental Design (LEED) program, but it embraces important differences that offer unique value to building owners and the green-building community.

RoofPoint evaluates a roof system in five categories: energy management, materials management, water management, durability/life cycle management, and innovation.

Since the beginning of 2011, RoofPoint projects have been certified in over 30 U.S. states as well as Canada and Mexico.

The January 2012 issue of Interface provides a complete overview of the program as well as the RoofPoint guideline, which is a comprehensive checklist of all critical environmental aspects of modern roofing systems.

Have you used RoofPoint on a project? Leave us a comment about the projects you have worked on that incorporate RoofPoint.

The invasion Orson Wells described so vividly on the radio October 30, 1938, was only sensational because of its time and place in history. What did Wells know about future events that we don’t know? Maybe he foresaw last year’s supernova or exploding star (it was best seen between the big and little dippers September 7-9, 2011), or the growth of solar power generation (photovoltaics = PV) or the implosion of Solyndra. Maybe he foresaw the green movement (little “green” men).

Now that I’ve got your attention, what does this have to do with today’s topic? Other than to introduce a discussion on the power of the sun, not much. Over the next two posts I will discuss photovoltaics (PV), a.k.a. solar power, its history, and the types available.

The most common type of solar module utilized today, crystalline silicon panels, are encapsulated in glass. They make up about 95% of all PV systems installed. Monocrystalline cells invented by Bell Labs in 1954 were cut as wafers from specially grown cylindrical silicon crystals. They are still among the most efficient PV systems, but they have poor tolerance for low light, are fragile and, very expensive, and require very heavy frames for rooftop mounting.

Polycrystalline cells are made from multiple sources and are not as dependent on perfect crystal growth. They are less expensive than monocrystallines, extremely fragile, and less efficient at converting sunlight to electricity.

While some crystalline manufacturers claim higher levels, typical silicone-based PVs have power production between 12 and 18 watts per square foot and operate with 14-20% efficiency. High temperature and shade reduce their output.

Thin-film PV systems don’t use crystalline silicon, but very thin layers of materials such as amorphous silicon, a mixture of copper-indium-gallium-diselenide (CIGS), or cadmium telluride. They can be flexible or rigid and can be adhered to a roof covering or rigid material.

First generation thin-films are mounted on a glass substrate and are relatively inexpensive to produce, but they are about 50% less efficient than monocrystallines. A heavy support frame is required and there have been issues with longevity and durability.

Second generation thin-films are mounted on a flexible substrate. They also do not require crystalline silicon and are easier to manufacture than first generation thin-films at the same cost. There is no requirement for special framing or support structures because they are much lighter than other PV systems. These thin-films are rugged and can often be integrated with modern roofing membranes after they are installed.

Because thin-films are typically surface-mounted, heat gain is an issue and these systems can compromise the benefits of reflective roof systems. Thin-film systems have power production of 5 to 10 watts per square foot and operate with 6-12% efficiency. Compared to crystalline silicon systems, thin-films are more effective in low light situations and are less affected by high temperatures.

In the concluding post I will introduce another type of rooftop power generation that produces electricity from the sun: Concentrated Solar Power, or CSP.

Rain. Snow. Wind. Sun. Salt. It’s a wonder that some things last as long as they do with all the weather variances we face. The roof is the important building component when it comes to weather protection and is the one thing that significantly protects the investment of the owner, by protecting the structure. Maintenance-free roofing systems do not exist, because all types of roofs require a certain amount of attention.

If you haven’t already done so, now is the perfect time to start an annual maintenance program. The importance is obvious – to extend the service life of the existing roof system. You want to catch problems early or even before they occur. Comprehensive repairs not only make the roof last longer, but also provide cost savings to the facility’s owner.

Perimeter

Walk the perimeter of the building to ensure that any unsecured objects, such as trash cans, signs, tree limbs, and loose building materials cannot become airborne projectiles during high winds. Trees should have all dead or broken branches removed and should be trimmed away from the building to prevent possible fires or damage to the roof.

Edges

Roof edge details should be checked to ensure that they are tight fitting and properly sealed. Corners of the building are the most susceptible to wind and rain damage. Immediately fix anything that lacks integrity.

Drainage

All debris and loose materials should be removed from the roof. Leaf grates, if part of the roofing system, should be cleaned and secured in a manner that keeps them in place. Make sure there is no blockage of any kind in drainage areas. Look for cracks or leaking on all areas of the roof and repair as needed.

Rooftop

Check all sealants on penetrations and terminations. All roof mounted equipment (HVAC units, satellite dishes, antennas, duct work, etc.) should be secured in a manner which will not allow movement. If it can be moved by hand it will become displaced in a storm or with wind. All service panel doors should be inspected to ensure that they are properly fastened. Any missing fasteners should be replaced.

A thorough maintenance program will address problems at their initial stage, minimizing or eliminating damage to interior furnishings, equipment, building materials and finishes. In this way, building owners avoid expenditures and preserve their investment, from top to bottom.

Metal roofing dates back to about 1000 B.C. when a temple in Jerusalem was built with a copper roof. Later on in human history, metal roofs caught on in certain parts of the world, like the Virgin Islands, and were effective for several reasons. They were strong enough to resist earthquakes, dramatic heat, and tropical hurricane winds. They also had an appealing look to them, which as we know, is very important in the design of structures.

Most people don’t know that there are really two types of standing seam metal roofs: architectural and structural. Architectural are those you can see from the ground. They are aesthetic in design and intended to look good on the building.

Architectural Standing Seam Roof

Structural standing seam roofs are flat/low-sloped roof decks that are intended to be more functional than aesthetic.

Modern metal roofs are among some of the most practical and long lasting available. They offer great security and protection to the building, and they are usually a reliable and worry free long-term choice. However time catches up with everything and rusted roof decks and leaks may start to compromise the building’s integrity.

With over 60 billion square feet of metal roofing in place in the United States and two billion more installed each year, that adds up to a lot of leaks – and a lot of money spent fighting them. When the integrity of the structural metal roof deteriorates, membrane retrofit solutions can provide a better option than replacing the metal roof or continuing to repair it. Membrane retrofits are a cost-effective, single-ply roofing solution that can usually be installed directly over existing metal roofs.

Duro-Shield Metal Retrofit Roofing System

We offer the Duro-Shield Metal Retrofit Roofing System to protect the building against rain, temperature changes, interior drips, ice build-up, as well as rust and corrosion. Our prefabricated membrane is custom designed to fit the metal roof exactly, and is assembled in our factory, eliminating 80-85% of rooftop installation labor. This solution keeps Mother Nature outside, while your inventory, equipment, and workers stay safe and dry inside.

Photovoltaic (PV) systems have been around for a while now, but the growth of rooftop PV installations has increased dramatically over the past few years. What is causing this surge?

There are many reasons PV systems make sense now and for the future. Energy costs will continue to escalate, and supply will continue to be chased by demand. Expanding the use of renewable energy sources such as PV can help meet some of the demand and relieve some of the cost pressures on electricity.

Rooftops are a good place to locate PV systems because they are typically little used and are free from obstructions that can hamper PV performance. Utilizing rooftops can also reduce land use, making it available for other purposes, or simply as green space.

PV is a clean, unobtrusive energy source, meaning that it does not pollute while it produces energy; eliminating the environmental issues associated with many other forms of electricity generation. The question arises as to whether the net benefits from PV electrical generation outweigh the monetary and environmental costs associated with production, installation, and disposal of a PV system. That analysis has not been done, but it could prove interesting.

Incentives from federal, state, and local governments and from utility companies can ease the financial burden of an investment in PV, plus encourage its introduction and the development of more cost competitive PV technologies. A good source of information on incentives is the Database of State Incentives for Renewables and Efficiency at www.dsireusa.org.

Increased use of PV can help reduce some dependence on foreign sources of fuel, leading to less potential for hardship due to supply disruptions.

While improving energy efficiency in buildings is essential (by way of reflective coatings, better insulation, high efficiency windows, day lighting, etc.), it cannot be the only component in pursuing Zero Net Energy Building design. Sources of renewable energy are necessary to supplement conventional sources.

Finally, as the cost of conventional energy sources goes up and availability goes down, the cost of solar electrical production is approaching parity with most conventional sources.

PV systems can be expected to last 20 years or more, so they should be paired with a roof system that doesn’t require much routine maintenance and has a similar lifetime.

From time to time we come across great articles on roofing that we feel are important to share with our readers. Recently, Kent Mattison, P.E., a senior consultant, president and partner with Benchmark Inc., a roof and pavement consulting firm in Cedar Rapids, Iowa, wrote a four part article for Facilities Net titled Roofing: Avoiding The Breaking Point. This builds on previous blog posts that we have shared regarding roof replacement. It explains not only the economic impact of roof leaks, but the safety hazards and impact it has on building occupants. It also touches on the importance of conducting an inventory and analysis of the roofs current condition and how it can help you plan and budget for future roof replacement. A product focus of different roofing systems is also included.

If you ever come across good roofing articles please let us know in the comments so we can share the information on our blog.

Be careful what you read! Are PTOs a new competitor in the roofing market? No, it’s an acronym with some misplaced letters from the title of a poorly written magazine article. So much marketing misinformation gets presented as fact that it’s a wonder anyone can make an informed roofing decision. Following is some information that may help in assessing the credibility of statements made about roofing.

PVC roofing is made from two basic components: fossil fuel and salt. Fossil fuel is converted to ethylene and rock salt goes through electrolysis to retrieve chlorine – one of the most abundant elements on earth. These components are combined to produce the vinyl chloride monomer which is used with other components to create PVC membrane.

Europe was early to adopt PVC roofing as a single-ply system of choice. Contrary to some claims, PVC roofing is being sold throughout Europe and in fact enjoys by far the largest market share of any of the thermoplastic single-plies.

White PVC membranes are among the most reflective on the market. The Duro-Last Cool Zone® membrane’s Solar Reflectance Index (SRI) of over 110 exceeds LEED requirements for Sustainable Sites Credit 7.2.

Recyclability is also a key element of many green design programs, and unlike other roofing materials, there are well-established programs for recycling PVC roofing membrane, including one offered by Duro-Last.

Because of its chlorine component, PVC is inherently flame resistant, unlike many other roofing products with higher carbon content. This makes fire ratings easier to achieve, and means that PVC roofing in general is less likely to emit toxic gases than other materials in building fires.

PVC membranes are highly flexible and can be custom-prefabricated before reaching the rooftop for installation. This reduces rooftop labor by minimizing jobsite welding by contractors. In addition, seam integrity is more reliable than for stiffer membranes that are made from materials other than PVC.

So, when evaluating systems for your next commercial roofing project, you may want to ask yourself “Why go with the PTO?” Check the facts; don’t be misled by misinformation, and make an informed decision.

Today is Earth Day and for building owners who are interested in “green” construction issues, the fact that old PVC roof membranes can be recycled may help improve your sales opportunities.

Unlike TPO, built-up, modified bitumen, and EPDM roofing systems, recycling programs for PVC roofing products have been in place for many years. The other types of roofing systems are much more likely to end up in a landfill once their rooftop service is complete.

Duro-Last established our “Recycle Your Roof” program for old PVC membranes in 2005. Material that we obtain from torn-off roofs is typically sent to Oscoda Plastics, Inc. in Oscoda, Michigan, which produces commercial flooring and expansion joints.

Details of the program, including our “Recycle Your Roof” request form, are available in Duro-Last Technical Bulletin #133, which can be downloaded here.

Here’s what the Tech Bulletin has to say about preparing the old roof for recycling:

Roofs and roofing materials that are broomed on the top and bottom surfaces may be considered for the Duro-Last Roof Recycling Program.

The top and bottom surface of the Duro-Last material must be free of stones, debris, fasteners, asphalt, coal tar pitch, and any foreign substances that may be attached or adhered to the material.

After brooming, cut the material free from the roof deck along both sides of the fastening tabs and all penetrations. Discard any heavily soiled or contaminated material. All returning material must be cut into 5 ft. x 5 ft. sections (or smaller), neatly stacked on a pallet and banded for shipping. Fastening tabs and fasteners must not be included in the recycle material.

The completed “Recycle Your Roof” form must be faxed or mailed to Duro-Last one week prior to the material being shipped.

Tip: Use a hook blade with a long handle to cut along fastening tabs.

The contractor pays for shipping to the closest Duro-Last manufacturing plant.

U.S. Department of Energy Secretary Steven Chu is a big proponent of cool roofing. In his July 2010 announcement, Chu made it clear that he was going to push for the installation of cool roofing systems on all federal buildings to help reduce energy usage. Secretary Chu is well-informed about cool roofing because he was formerly the head of Lawrence Berkeley National Laboratories (LBNL), the entity that pioneered the study of Urban Heat Islands (UHIs).

Not only will cool roofing reduce building energy usage, it will also help mitigate the UHI effect. The UHI effect is the tendency for urban areas to be hotter than surrounding areas. LBNL found that the average temperature on a hot summer day will be seven degrees warmer in North American urban areas than surrounding rural areas. During an extended heat wave the difference can be even more pronounced. Studies have shown that there are three primary factors that cause the majority of the UHI effect.

Vegetation

The first factor is that urban areas have less vegetation than rural areas. Not only do trees and shrubs provide shade, but thriving vegetation keeps itself cool through a process called evapotranspiration. Similar to how the human body sweats to keep itself cool, vegetation releases moisture to stay cool. About 56%, or almost four degrees, of the seven degree difference is due to less vegetation in urban areas than rural.

Dark Pavement

Many might think that dark pavement would account for much of the UHI effect. While walking down a city street, one can feel the heat radiating up. But dark pavement accounts for only 6%, or less than one-half degree, of the seven degree difference.

Dark Roofing

Roofing takes up a lot of surface area in urban areas, but roofing is not often considered a source of urban heat because it is “out of sight, out of mind.” Yet dark roofing accounts for 38%, or almost three degrees, of the seven degree difference associated with UHIs.

Many cities have attempted to increase green space and vegetation through civic programs and building codes, but for every tree planted or park developed there is much more green space that succumbs to urban sprawl. Green space initiatives are at best a long term means of mitigating UHIs and can entail significant expense.

Paving products made from lighter colored materials are available, but implementing these measures is capital intensive and can take years to accomplish. And considering the relatively minor role that paving plays in UHIs, there are options that provide more bang for the buck.

Installation of cool roofing during initial construction or when re-roofing offers immediate benefits, not only toward mitigation of UHIs but to the building owner in the form of energy savings. A good roofing system is essential for protecting any building from the elements. Selecting and installing a cool roofing system is easy to accomplish, inexpensive relative to other UHI mitigation efforts, and provides benefits immediately.

Even in northern geographic areas where net energy savings may be minimal, cool roofing systems offer significant benefits that may be less tangible but are essential to the long term performance and durability of the roof, insulation and HVAC equipment.

From time to time we come across great articles on roofing that we feel are important to share with our readers. Recently, Karen Warseck of Facilities Net wrote an article titled How To Inspect A Roof. This builds on previous blog posts that we have shared regarding roof inspection. It explains not only the importance of getting up on a roof and doing some preventative maintenance, but also the importance of keeping records in order so that if you do have a problem you will know if your roof is still under warranty and who you should contact first.

If you have any tips for inspecting a roof please share them with us in our comments section.